The surf zone of sandy beach in Tian’ao lies in a typical island harbor in the south of the Sijiao Island. In order to find out if there is any diurnal variation of species composition of larval and juvenile fishes, samplings were taken in surf zone of Tian’ao during the spring tide each month from October 2010 to September 2011 (seine net 1 m×4 m, 1 mm mesh aperture). A total of 33 species, 22 families, 484 individuals were collected which could be divided into 4 ecological patterns (marine fish 14; estuarine fish 11; migration fish 6; freshwater fish 2). The most abundant species Liza haematocheila was 29.5% of total individuals. The CPUE and species number of larval and juvenile fishes in the daytime were significantly higher than those at night(P<0.01). We also find out that CPUE of larval and juvenile fishes shows special distribution during different time periods in 24 h especially in the day time. There were more individuals collected during 6:00 8:00 and 14:00 18:00 than the rest of the 24 h. And the species numbers were higher during 6:00 8:00 and 12:00 18:00 than the rest of the 24 h. The results showed that larval and juvenile fishes prefer staying in shallow waters of surf zone in the daytime, and they had no obvious selection for surf zone in the night.